A Definition of Physical Fitness

Bottom Line Up Front: Physical fitness is measured by how well you look, feel, and perform (as Robb Wolf loves to say). Your physical fitness will be influenced by four things: Nutrition, Sleep, Stress, and Activity. Note that I didn’t list exercise at all! This is because exercise is a sub-category under Activity. How well you eat, how much and well you sleep, how much stress you have, and how active you are will be what determine your level of physical fitness.

Physical Fitness

Let’s look at of the factors that make up physical fitness, how to measure physical fitness, and a brief history of my arrival at this definition.

General Physical Skills Without Pain

I think the definition CrossFit uses for measuring physical fitness is sound. They contend there are ten recognized general physical skills which are cardiovascular/respiratory endurance, stamina, strength, speed, flexibility, power, coordination, agility, balance, and accuracy. These cover the gamut of things you would need a physical body to do in any situation; most things you do are a combination of many skills at once.

However, I think they are missing a major factor: PAIN!  While it is impressive to deadlift 500 lbs, run a 6-minute mile, be flexible, have balance, be coordinated, etc. it isn’t as impressive if you can’t do them without being pain free.  I think it is important for total fitness to be able to do these things in many conditions, in many ways, without any pain. When I talk about moving well, I am talking about this. Moving well will keep you pain free and resistant to injury. Mobility, pre-hab, prep work are all terms that you will hear that get after this idea.

I think it is also important to tie in how you look as well (body composition) to physical fitness.

In sum, defining your physical fitness should be how well you do at the general physical skills, how well you move, i.e. how little pain you have while moving, and how your body looks.

My History

I started lifting weights to prepare for football when I was 14. I fell in love. I would have defined fitness as simply about performance then. Plain and simple: how big, fast, and strong you are. I didn’t believe anything else mattered much as long as you trained hard.

As I got into my 20s, I realized nutrition mattered, but it was a far second to exercise (not activity, mind you but just exercise). I did a lot of low fat, high protein, high carb for many years. I read a ton about exercise, some about nutrition.

I will spare you the next few decades of learning and get to the point:

  • I went from thinking exercise was 90% of fitness to believing it is 10%.
  • I went from not considering sleep important at all, to placing it higher than exercise and seeking to protect it like my gym time. I am on a mission to debunk the idea that it is a badge of honor to sleep as little as possible in the Army.
  • I went from never even considering how much or how well I “move” to using a standing desk at work and always wearing minimalist shoes (or no shoes whenever I can!).
  • I went from thinking walking was for the lazy who couldn’t take intensity to walking religiously and wearing a pedometer every day.
  • I went from thinking mobility work was something for pro athletes to placing it in every single workout I do.
  • I went from low-fat, high protein, and no regard for “real food” to a Paleo diet based on the idea that eating real food trumps all and that quality of nutrients is vital. I was a vegetarian/vegan for more than five years, so I have a wide variety of experiences.

If I had to rank the elements of fitness today, I would say they are Nutrition first, then Sleep, then Stress, then Activity, with exercise as a small subset of Activity. There is some debate in my head as to whether it’s Sleep or Stress as second, but there is no debate as to Activity being last.

In the past I would have had Exercise a far first (no consideration of Activity), then Nutrition with no regard for Sleep or Stress.

Let’s explore in a more detail the elements of physical fitness.


Of all the areas of fitness, this one can stand above the others because I believe it pervades all of them. You will not sleep well, move well, or be mentally fit if your nutrition is lacking. I have tried nearly every diet/technique you can find. I will tell you it wasn’t until I realized these things that I made meaningful progress with my fitness:

  • Eating real food matters. I used to only think macronutrients mattered, i.e. how much protein, fat, and carbs I was taking in. I didn’t think it mattered where it came from. The day I made a change to eating real food (things without ingredients like beef, broccoli, apples, sweet potatoes, etc.) I made noticeable progress in appearance and performance.
  • Fat should be the basis of your diet.
  • Saturated fat isn’t bad for you and is in fact preferred.
  • Quality of food matters. Grass-fed beef is not the same as mass-produced grain-fed beef.
  • Fasting is good for you when done correctly. It is OK not to eat despite what you heard about breakfast being the most important meal of the day. I usually don’t eat until noon.
  • Our government has lied to use for decades. We moved to a grain-based diet many decades ago, and it is a root cause of our health problems.
  • All people should eat basically the same, with adjustments. A 50-year-old woman should be eating the same way as a 25-year-old special operator – real food of high quality in amounts that support activity. The differences will be in the amounts of protein, fat, and carbs based on their activity levels. This gets complicated, but the bottom line is more carbs for more intense activity. Most Americans will do fine with a low to moderate carbohydrate content (100-150g). CrossFit athletes with high glycolytic demands will need more carbs generally.


While there may be variations, most research I have seen supports about 8 hours for most people every night of uninterrupted sleep. Merely being asleep doesn’t equal good sleep. Dark room, cool temperature, avoid electronics prior (they disrupt melatonin release) are the basics.


Managing what is happening in your head has drastic effects on your life. When you are stressed, your hormones are out of whack. Your body is in an altered state and in survival mode. That means excess cortisol release, poor glucose metabolism, bad recovery, etc. It is a terrible thing. Figuring out how to de-stress yourself through working on maintaining healthy relationships, having hobbies, and finding meaning in your life really matter. I have found improving productivity is a way that keeps me from stressing out and why I feel it is so important to fitness. When I feel like I have a system to manage the chaos of everyday life, I feel in control. Feeling like you are barely getting by in life will stress you out all day. Your sleep will suffer, you will crave “bad” foods, you will be distracted in the gym.


This includes how much you move every day, how well you move, and how you feel while moving. We are talking about your physical body here. Your fitness in this category will be defined by how much you sit, how strong your feet are, your posture, and your performance (strength, speed, flexibility, etc.). To be clear, “exercise” is a dedicated, timed bout of physical activity usually with performance-based goals. Doing 10 x 400m sprints is exercise. Doing any CrossFit workout is exercise. Going for a daily walk isn’t. It is just physical activity. Same goes for playing soccer outside with the kids – just activity. If you are fit, you can accomplish every day tasks without pain. Can you play outside with your kids and not get out of breath? Do your knees ache if you sit in the car too long? Does it hurt to get out bed? Are you sore for a week after playing golf? You also should be able to do all the basic human movements like bend, squat, run, lift things over your head, hang from a bar, etc. without pain or limitation. Are you able to run two miles in 13 minutes but can’t even touch your toes? Can you deadlift 500 pounds but not even do one pull-up? You have glaring weaknesses you need to address. Simply doing a variety of basic activities without ever lifting a weight is more than enough to be fit. Going for a hike, long walk with the dog, playing on a jungle gym, carrying your bags for a round of golf, and carrying your young kid around on a shopping trip are all great ways to maintain your activity levels. Some will want to get into strength and conditioning (performance). You do not need to in order to be fit. It took me decades to believe this. Mark Sisson’s Primal Blueprint Fitness is the best simple way of getting after this in a concise way. His laws are in accordance with how humans have evolved to move: Move at a slow pace often, lift heavy things, and sprint once in a while. And while we are on the subject, distance running is, in my opinion, the least valuable form of exercise BY FAR. Somewhere in the 1970s people started to “exercise” and distance running seemed to be what would be the healthiest thing to do for your heart. This spawned the bullsh*t running shoe industry. When most people think of exercise, they think of distance running. While it definitely fits into a diverse activity regimen, I would be happy to completely eliminate anything over 800 meters for most people all of the time. I will expand on why it is so useless in future posts.

QUESTION: Do you have anything to add to the definition of physical fitness? What does it mean to you? Post thoughts to comments.

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